ARC Data Online: http://www.arcdataonline.com/
ArcData Online is ESRI's Internet Mapping and Data Site. The site contains a wide range of geographic information that users can access to create map images and download data.

Columbia Ecosystem: http://www.icbemp.gov/spatial/metadata/phys/phys.html

ESRI Virtual Campus: http://campus.esri.com/free/
ESRI's virtual campus. They have some valuable free GIS tutorials and it only takes a moment to set up a free account.

Geographic Information Systems at Boise State University: http://earth.boisestate.edu/gis/
Homepage for BSU's GIS center offering resources in training, teaching, research & development, and the promotion of partnerships.

GIS FAQ Page: http://www.census.gov/ftp/pub/geo/www/faq-index.html
Assorted, interesting information about GIS.

Idaho Geographic Information Center: http://www.idwr.state.id.us/gisdata/gis.htm

Idaho State University Geographic Information Systems Center: http://giscenter.isu.edu/
Homepage for ISU's GIS center offering resources in training, teaching, research & development, and the promotion of partnerships.

Montana Natural Resource Information System: http://nris.state.mt.us/
Montana's NRIS program is a GIS based state office that manages a variety of natural resource data.

US Environmental Protection Agency (EPA): http://www.epa.gov/nsdi/index.html
Access to GIS Spatial Data Sites at federal, state and local levels by different environmental subjects.

USGS GIS Information Page: http://www.usgs.gov/research/gis/title.html
Useful information for understanding the applicability and functionality of GIS.

University of Idaho GAP Analysis: http://www.wildlife.uidaho.edu/idgap.htm

University of Idaho "Inside": http://inside.uidaho.edu/